\(a,\dfrac{-5}{6}=\dfrac{-20}{24}\\ \dfrac{7}{-8}=\dfrac{-21}{24}\)
Vì \(\dfrac{-20}{24}>\dfrac{-21}{24}\Rightarrow\dfrac{-5}{6}>\dfrac{7}{-8}\)
\(b,\dfrac{3}{2}=\dfrac{45}{30}\\ \dfrac{4}{3}=\dfrac{40}{30}\\ \dfrac{-2}{5}=\dfrac{-12}{30}\)
Vì \(\dfrac{45}{30}>\dfrac{40}{30}>\dfrac{-12}{30}\Rightarrow\dfrac{3}{2}>\dfrac{4}{3}>\dfrac{-12}{30}\)